The dodecahedral (H2O)(20)(-) and (H2O)(21)(-) clusters are studied by applying the Becke-3-parameter density functional theory and Lee-Yang-Parr correlation functional. The geometry optimizations are carried out with 6-31G(*) basis set followed by single-point calculations for energy and charge distribution values with 6-311++G(**) basis set. While the structures of these clusters are very similar to their neutral counterparts, the charge distributions are significantly different. In the dodecahedral (H2O)(20)(-) cluster with an empty cavity, the -1 charge is distributed almost evenly among the half of the water molecules (10) on the cage surface. However, in a filled dodecahedral (H2O)(21)(-) cluster, the -1 charge is almost entirely localized unto the water molecule in the cavity. The calculated electron binding energies for the (H2O)(20)(-) and (H2O)(21)(-) clusters are 0.805 and 1.12 eV, respectively, and the stabilization energies relative to monomers and separated electron are 202 and 214 kcal/mol, respectively. (C) 2003 American Institute of Physics.